Comparative study on the pregnancy outcomes of in vitro fertilization-embryo transfer between patients with different ovarian responses (a STROBE-compliant article)

Comparisons of benefits and risks of single embryo transfer versus double embryo transfer: a systematic review and meta-analysis

BACKGROUND

Evidence referring to the trade-offs between the benefits and risks of single embryo transfer (SET) versus double embryo transfer (DET) following assisted reproduction technology are insufficient, especially for those women with a defined embryo quality or advanced age.

METHODS

A systematic review and meta-analysis was conducted according to PRISMA guidelines. PubMed, EMBASE, Cochrane Library and ClinicalTrials.gov were searched based on established search strategy from inception through February 2021. Pre-specified primary outcomes were live birth rate (LBR) and multiple pregnancy rate (MPR). Odds ratio (OR) with 95% confidence interval (CI) were pooled by a random-effects model using R version 4.1.0.

RESULTS

Eighty-five studies (14 randomized controlled trials and 71 observational studies) were eligible. Compared with DET, SET decreased the probability of a live birth (OR = 0.78, 95% CI: 0.71-0.85, P < 0.001, n = 62), and lowered the rate of multiple pregnancy (0.05, 0.04-0.06, P < 0.001, n = 45). In the sub-analyses of age stratification, both the differences of LBR (0.87, 0.54-1.40, P = 0.565, n = 4) and MPR (0.34, 0.06-2.03, P = 0.236, n = 3) between SET and DET groups became insignificant in patients aged ≥40 years. No significant difference in LBR for single GQE versus two embryos of mixed quality [GQE + PQE (non-good quality embryo)] (0.99, 0.77-1.27, P = 0.915, n = 8), nor any difference of MPR in single PQE versus two PQEs (0.23, 0.04-1.49, P = 0.123, n = 6). Moreover, women who conceived through SET were associated with lower risks of poor outcomes, including cesarean section (0.64, 0.43-0.94), antepartum haemorrhage (0.35, 0.15-0.82), preterm birth (0.25, 0.21-0.30), low birth weight (0.20, 0.16-0.25), Apgar1 < 7 rate (0.12, 0.02-0.93) or neonatal intensive care unit admission (0.30, 0.14-0.66) than those following DET.

CONCLUSIONS

In women aged < 40 years or if any GQE is available, SET should be incorporated into clinical practice. While in the absence of GQEs, DET may be preferable. However, for elderly women aged ≥40 years, current evidence is not enough to recommend an appropriate number of embryo transfer. The findings need to be further confirmed.

The Influence of Chromosomal Polymorphism on Embryo Development and Embryonic Molecular Karyotype in Preimplantation Genetic Testing for Chromosomal Translocation

Traditionally, chromosomal polymorphisms (CPMs) are normal genetic variants in individuals with no phenotypic variations. However, some studies have shown that CPM is related to reproductive diseases. We explored the influence of CPM on embryonic development and molecular karyotype in chromosomal translocation (CT) patients undergoing preimplantation genetic testing (PGT) between February 2013 and May 2019. Twenty-six cases with CPM and 56 controls with normal chromosomes were included. Furthermore, a 1:4 match pair analysis by female age included 39 cases with CTCPM and 185 controls with CT. There was no statistical difference in fertilization rate (78.48% vs. 78.33%), cleavage rate on Day 3 (90.32% vs. 89.16%), blastocyst rate (60.00% vs. 60.80%), and the high-quality blastocyst rate (36.31% vs. 35.22%) between CPM and normal chromosomes. The high-quality blastocyst rate of CTCPM was significantly lower than that for CT (26.78% vs. 38.89%). Moreover, there was no statistical difference in fertilization rate (70.65% vs. 70.37%), cleavage rate on Day 3 (88.67% vs. 89.53%), and blastocyst rate (48.48% vs. 53.17%) between CTCPM and CT. In addition, one CTCPM spouse had a lower high-quality blastocyst rate, especially of males with CTCPM. Abnormal embryo rates of CTCPM were significantly higher than those for CT (78.64% vs. 68.93%). Abnormal embryo rates were higher in both CTCPM and CPM paternal carriers with CT partners, respectively. For CT, CTCPM may have an impact on the high-quality blastocyst rate and embryonic molecular karyotype, especially in male patients. Patients with CTCPM are relatively rare, but this population would benefit from being explored using a larger sample size.